Models and Theories in Human-Computer Interaction/The Economics of TAM
The Technology Acceptance Model (TAM) is a model for describing the likeliness of an innovation’s usage by a user based on self-percieved notions of usefulness and ease of use.
The increasing ubiquity of technology has greatly changed the implications of TAM, which was originally developed at a time where technology was only available at the workplace. Today, the role of technology has expanded to every aspect of our daily lives. In effect, the decision to adopt a technology has an increasingly prominent impact in day-to-day events.
Unfortunately, the validity of TAM has historically relied on self-assessment methods in studies with users. These methods rely on the assumption that a person can accurately assess and report his/her emotional experiences. While self-reports offer insights into the subjective user experience, they do not explain the rationale behind user behaviors.  Therefore, models that help explain the human decision making process should be examined for usage in conjunction with TAM.
In economic theory, human behavior is similarly modeled on one’s own perception and their actual actions though the model of the Economic Man.The Economic Man model depicts human actions as the result of choosing the best option based on the fulfillment of his or her "utility function", meaning the ability to maximize any situation that involves choice. Adam Smith’s Wealth of Nations introduced the idea of the Invisible Hand, a subconscious force in free markets to adjust prices through the collective self-interested actions of all individuals. Smith proposed that the economic man is driven by a relentless desire to improve his condition; a common self-seeking trait of humanity.  This model of humanity proved instrumental in relating economic behavior to individual psychology and shaped the course for modern economic theory.
The underlying human factors principles of HCI has allowed for widespread multidisciplinary integrations within the field. The commonalities between the two models and their focus on subconscious human motivations for predicting actual behavior is representative of the basis of human nature. Ease of use and usefulness are directly applicable to the economic human variable of utility. If a user does not think an innovation will add to their utility, then they will not adopt its usage into their processes.
By combining the similarities of TAM and the Economic Man, we can further explore the user's rationale behind their decision to use a particular innovation, which could lead to a more comprehensive understanding of user behavior.